As is known, the lighter body serves as a receptacle for a removable heating plug equipped with a heating body to light the cigar or the cigarette and comprises an electrically conductive lighter socket, with a bottom, internally bearing with electrical insulation provided, by means of an attachment device and a first electrically insulating part, a connection member usually in the form of a bimetallic strip with a base and axially oriented blades originating from the said bottom and directed towards the open end of the lighter socket.
More precisely the plug has a cup surrounding the heating body and the blades of the connecting bimetallic strip each have a hook-shaped free end, so that a clip is formed which is able to cooperate with the cup of the plug to keep it in the heating position and to establish an electric circuit by means of power supply parts borne by the lighter socket and connected to the terminals of the voltage source, namely the battery in the case of an application to a motor vehicle.
When the heating body reaches a sufficiently high temperature, the blades of the connecting bimetallic strip expand to interrupt the circuit.
In certain cases, these blades may accidentally remain in contact with the cup although the heating body has reached the required temperature.
This may be a cause of fire due to the fact that the fixed wall on which the lighter body is mounted is usually made of plastic material.
For this reason a safety element which consists of a blade forming a bimetallic contactor forming an integral part of the connecting bimetallic strip was specified in document FR-A-2 655 927.
This blade extends axially in the opposite direction to the blades of the bimetallic strip and for this purpose passes through the bottom of the lighter socket by means of an opening.
This blade is able to come into contact with a plane portion belonging to the power supply part connected to the terminal of the battery to establish a complete short circuit thus causing a large increase in the electric current, which immediately blows the fuses protecting the cigar lighter and prevents the fact that the heating plug is kept in the heating position from producing a fire.
This arrangement makes it not necessary to increase the axial length of the lighter socket and this safety blade is sensitive to the temperature of the connecting bimetallic strip so that it may be traversed by a large heat flow in contrast to the arrangement described in document DE-A-1 950 758 in which the safety blade is mounted outside the lighter socket to come into contact with a metallic attachment shell surrounding this socket by being fixed thereto by screwing.
This blade is then insulated in relation to the socket and is sensitive to the temperature of the connector member via the attachment device so that the heat flow is not very large.
In practice in document FR-A-2 655 927 this safety blade bears a contact stud able to cooperate with a plane portion belonging to the power supply part connected to the negative terminal of the battery.
This part, hereinafter called the second power supply part, is disposed outside the lighter socket whilst being connected electrically to the bottom thereof, whereas the other power supply part, hereinafter called the first power supply part, is connected to the connecting bimetallic strip via the attachment device with the intervention of a second electrically insulating part inserted between the said power supply parts.